Spring balances are often used in sash windows, to support or counterbalance the weight of each window sash. A balance is fitted on either side of each sash. The balances work by winding up a helical spring which then produces a frictional engagement between two parts, one connected directly or indirectly to the frame and the other connected directly or indirectly to the sash. The friction is such that the sash will stay put in any position to which it is moved, but can be overcome, so that the sash can be moved, when pushed up or down by an external force. The tension in the springs in the balances have to be set in accordance with the weight of the particular sash being supported. The tension is adjusted by rotating a component of the balance which is to be connected to the sash, while that component is momentarily disengaged from the sash.
This rotation is difficult to do, because access to the relevant component is restricted by the adjacent parts of the window frame. Also it is difficult to adjust the balances on both sides of a window so that they are under equal tension. Still further, readjustment may be necessary after the window has been in use for a period of time.
Sash windows are known where the sashes are supported on slide shoes which slide in channels in vertical window frame members. The sashes are pivotally mounted in these shoes so that the sash can be pivoted out of the plane of the window frame. Such sashes are also provided with secondary fastenings to normally hold the sashes in the window plane, but those secondary fastenings can be released when the window is to be pivoted.
The invention seeks to provide a mechanism which overcomes or reduces the difficulty of spring balance adjustment when slide shoes are used.